The effects of arsenic speciation on accumulation and toxicity of dietborne arsenic exposures to rainbow trout

• Published in: Aquatic toxicology 2019-05, Vol.210, p.227-241
• Main Authors: Erickson, Russell J., Mount, David R., Highland, Terry L., Hockett, J. Russell, Hoff, Dale J., Jenson, Correne T., Lahren, Tylor J.
• Format: Article
• Language: English
• Subjects: Accumulation; Animals; Arsenates - metabolism; Arsenates - toxicity; Arsenic speciation; Arsenicals - metabolism; Arsenites - metabolism; Arsenites - toxicity; Cacodylic Acid - metabolism; Cacodylic Acid - toxicity; Diet; Dietborne exposure; Food Chain; Growth; Mining; Oligochaeta - metabolism; Oncorhynchus mykiss - metabolism; Rainbow trout; Rivers - chemistry; Water Pollutants, Chemical - metabolism; Water Pollutants, Chemical - toxicity
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/j.aquatox.2019.03.001

•Dietborne toxicities of three organoarsenicals to rainbow trout were much less than inorganic arsenic.•Inorganic arsenic toxicity to rainbow trout is similar for live and pellet diets.•Absolute and relative amounts of arsenic species in trout diet items vary greatly.•Dimethylarsinate is more toxic than arsenite in waterborne exposures to oligochaete worms.•Size-dependent growth rates can confound interpretation of toxic effects on fish growth. The effects on juvenile rainbow trout survival, growth, food consumption, and food conversion efficiency from dietborne exposures to inorganic arsenic (arsenite, arsenate) and to the organoarsenicals monomethylarsonate (MMA), dimethylarsinate (DMA), and arsenobetaine (AsB) were investigated in two experiments: (1) a 28-d exposure using live diets of oligochaete worms separately exposed via water to these five arsenic compounds and (2) a 56-d exposure using pellet diets prepared from commercial fish food to which arsenite, MMA, or DMA were added. In the live diet experiment, the degree to which worms could be contaminated with the organoarsenicals was limited by toxicity to the worms and other experimental constraints, so that their toxicity relative to inorganic arsenic could not be fully established, but AsB was concluded to have low toxicity, consistent with published results for mammals. For the pellet diet experiment, MMA and DMA were found to be at least an order of magnitude less toxic than inorganic As on the basis of concentration in the diet, as well as much less toxic on the basis of accumulation in the fish. The need to consider speciation in aquatic risk assessments for arsenic was further demonstrated by tissue analyses of three macroinvertebrate species from a mining-impacted stream, which showed large variations in both total arsenic and the relative amounts of inorganic and organic arsenic. Additionally, although effects of arsenic on trout appear to be well correlated with inorganic arsenic, worms were found to be more sensitive to waterborne DMA than to inorganic arsenic, showing that low toxicity of organoarsenicals cannot be assumed for all aquatic organisms. Various difficulties in evaluating and applying studies on dietborne exposures and fish growth are also discussed.